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Full text of "Practical Organic Chemistry"

ROTATION   OF TARTARIC ACID

and /'/the density of the solution. The specific rotation of dis-
solved substances varies with the concentration and with the
temperature.

Heat some tartaric acid in an air-bath to 110, until it is quite
dry. Weitfh accurately about 20 grams of the dry acid and
dissolve in water ; then make up the solution to exactly 100 c.c.
Determine the rotation of the solution in a 200 mm. tube, and
note the temperature at which the observation is made.

Take 50 c.c. of the solution and dilute it to 100 c.c. Deter-
mine the rotation of this solution tif ///< same fcmpcmhtrc as
that at which the first rotation was observed.

Dilute' 50 c.c. of the second solution to 100 c.c., and a^ain
determine the rotation at the same temperature.

The same process can be repeated once or twice more. Cal-
culate the specific rotation of the tartaric. acid, usinjj the Iirst
formula. Plot the results on squared paper, making the ordi-
nates specific rotation and the abscissae concentration.

Example :

Temp.

IO

10"
10"

Concentration.

40
2O
IO

Length of tube.

Auyjc of Rotation.
	Spec. Rut. '^'"

6"
	!-   7*5"

3 59'
	I   <r<K>"

2"  II'
	i 10-91"

(Krcckc, />V.v.//.'//,' ,SWmv//<v///V, p. :-.;;.)

The following table shows the influences of temperalinv on
the specific rotation of an aqueous sululion containing 20 grains
of tartaric acid in roo c.c.

o

10"
20

40
60

So0

100


	K,,,:,,i,,
	Sprrilir 1
	,!.

3
	2,X'
	!    S
	oO"

3
	5<i'
	-1   o
	()(>''

4"
	?<v*'
	1   II
	57"

5"
	2S'
	-1 rj
	00"

<r
	2S'
	-1 lO
	10"

7"
	2l'
	( iS
	3^

8
	*<>'
	1 21
	50'

(Thoniscn,,/. prakt. Ck, (a) r-', an.)